US838349A - Process for producing zinc lithographic plates. - Google Patents

Description

CHARLES G. MEYN, OF ROCHESTER, NEW YORK.

PROCESS FOR PRODUCING ZINC LITHOGRAPHIC PLATES.

Specification of Letters Patent.

Patented Dec. 11, 1906.

Application filed March 9, 1906. Serial No. 305,077.

To all w/wm, it Huey concern:

Be it known that 1, CHARLES G. MEYN, a citizen of the United States,and a resident of Rochester, in the county of Monroe and St ate of- New York, have invent ed certain new and Y useful Improvements in Processes for Producing Zinc Lithographic Plates, of which the following is a specification.

This invention relates to the production of surfaces on zinc plates for lithographic printing. Its object is to produce economical and durable lithographic plates of a character capable of reproducing fine work.

The Zinc-plate is first cleaned with a suitable acid cleaning mixture and is then grained by any means suitable to produce a fine grain on the plate and is then washed and dried. The plate is then coated with a suit able sensitizer, such as a solution of acetic acid and alum, and after drying is ready for the reception of a transfer or of a lithographic drawing.

If a transfer is employed, it is properly applied to the plate and in the usual manner the paper is soaked off, the plate is dried, and is coated with a solution of gumarabic and dried again. The gum-arabic protects the surface of the plate except over the greasy transfer-ink. Then an asphaltum etchingground is applied to the whole surface of the plate and is spread thereon by a soft cloth. This etching-ground replaces the transfer-ink and is also spread over the surface of the gum-arabic. Then the plate is washed with water, whereby the gum-arabic is dissolved and is removed from the plate, together with the etching-ground lying upon it. The plate is then dampened and is rolled up with greasy lithographic ink and is powdered in the usual way with an etching-powder. The greasy ink clings to the etching-ground, which lies upon the surface originally cov ered by the transfer-ink, and the etchingpowder clings to the greasy lithographic ink. The plate during all the time subsequent to the application of the etching-ground is keptmoist in order that the lithographic ink shall be repelled from all parts thereof except those parts originally occupied by the lines of the transfer. Next the p ate' is etched in a moving bath with the etching and surfacing fluid described below. This etching is con ducted for a suitable length of time, which must be judged by the lithographer, and thus a surface is produced on the plate outside of the original lines occupied by the transfer, which surface absorbs and retains a film of water. Then the plate is washed free from acids and is coated again with a solution of gum-arabic in water, which clings to the plate, except over the portions coated by the lithographic ink. The gum-arabic is dried, and then the etching-ground is spread a second time over the plate with a soft cloth, and the plate is ready for printing.

A suitable prepared asphalt etching-ground for the purposes above mentioned is a commercial article and is composed of soap, rosin, asphaltum, turpentine, and sometimes a little lavender-oil.

The etching and surfacing fluid above mentioned is ordinarily composed of one dram of muriatic acid, two drams of acetic acid,

(strongest commercial,) one-half ounce of plrimacid, one-quarter ounce of hos horic acid and one-half dram of powc ered copperas in about a gallon of water. These proportions may be varied .within reasonable limits. Where the etching must be rapid, the proportion of copperas is increased, and where the etching is to be slow the proportion of copperas is decreased, or that ingredient is omitted entirely. Where a drawing is made upon the prepared zinc with the lithographic ink called tuschflg. or with lithographic crayons, about twenty-four ounces of gum-arabic are added to the abovementioned etching and surfacing fluid. This etching and surfacing fluid used in the manner above stated produces a lithographic plate which is not intended or suitable for use in place of a wood cut or engraving, but is truly a lithographic plate and requires the employment of a film of water clinging to the absorbent surface above mentioned, whereby lithographic ink is repelled therefrom and clings only to the portions of the plate from which the said absorbent surface is absent. The surface produced by the above mixture in substantially the proportions above stated is exceedingly durable, hard, delicate in grain, and absorbent of water, whereby a zinc plate may be employed for many times the number of lithographic impressions which heretofore have been successfully printed from Zinc lithographic lates.

Any lithographic p otographer will employ a photographic method with a zinc plate without further instruction, as the film of chromated material becomes insoluble under those parts of the negative that transmit light, which are those parts of the negative that must be reproduced in black. The remainder of the material remains insoluble and can be Washed ofi. The insoluble material therefore takes the place of the transfer in the initial stages of the process above described. After the soluble material is removed the process continues as above described.

What I claim is 1. The process of producing lithographic zinc lates, consisting in producing a Water absor bent and retaining surface thereon outside of the printing surface or lines by acting upon said plate by a mineral-acid solution in combination with phosphoric and acetic acids.

2. The process of producing lithographic zinc lates, consisting in producing a Water absor bent and retaining surface thereon outside of the printing surface or lines by acting upon said plate by a mineral-acid solution in combination with phosphoric and acetic acids and copperas.

3. The process of producing lithographic Zinc plates, consisting in producing a Water absorbent and retaining surface thereon outside of the printing surface or lines by acting upon said plate by a mineral-acid solution in combination With muriatic and nitric acids, phosphoric and acetic acids, substantially in the proportions above set forth.

4. The process of producing lithographic zinc plates, consisting in producing a Water absorbent and retaining surface thereon outside of the printing surface or lines by acting upon said plate by a mineral-acid solution in combination With muri-ati'c and nitric acids, phosphoric and acetic acids and copperas, substantially in the proportions above set forth.

CHARLES G. MEYN.

Witnesses D. GURNEE, J. C. MEYN.